Owning your own home

Continuing on from the 'gap between my new skirting and wall is cavernous' saga, next instalment is 'holding up a straight edge to a newly plastered wall is impossible as the wall deviates at two different angles where the scrim tape meets'.

I'm at my wit's end. Surely, surely a newly boarded and plastered wall should be straight, at the very least?!

I have the main contractor in tomorrow. Am I overreacting to point out:

• angle of wall changes where boards have been joined
  
• board joins are clearly visible through the skim
  
• plaster is exceptionally rough around the edges of the room (like it's been painted on?)
  
• at least one screw head visible through the skim
  
• slim feels very thin to the touch. I'm no expert of course, but this skin doesn't have tha lt lovely 'glassy' feel to it - instead it's like the paper applied to the surface of the boards.
  
  

I'm simply going to point out that reasonable skill and care has not been taken in the work and I expect a reskim(?) and skirting etc refitted at no extra cost. I'll be withholding 10% of contract price until then. No issues there, right? Would a reskim (by a different plasterer...) be helpful at all?